32 



Chevalier G. Marconi 



[March 3, 



demonstrating on theoretical grounds the existence of electro-magnetic 

 waves, fundamentally similar to but enormously longer than waves 

 of light. Following up Maxwell, Hertz in 1887 furnished his great 

 practical proof of the existence of these true electro-magnetic waves. 



Building on the foundations prepared by these great men, the 

 author carried out in 1895 and 1806 his first tests, with apparatus 



Fig. 3. 



which embodied the principle on which long-distance wireless tele- 

 graphy is successfully worked at the present day. This early arrange- 

 ment is shown in Figs. 1, 2, and 3. 



In Figs. 1 and 2 are shown diagrammatically the complete trans- 

 mitting and receiving plants, and in Fig. 3 are shown the circuits of 

 the receiving instruments. 



The main feature of the system is the utilisation of the earth- 

 effect by connecting both tlie transmitting and receiving instruments 

 between earth and a raised capacity. 



The later improvements introduced in the author's system of 

 wireless telegraphy have been directed towards the following ends : — 



1. To obtain independence of connnunication, or the prevention- 

 of interference between several neighl^ouring stations. 



2. To increase the distance of communication. 



3. To increase the efficiency of the apparatus, its accuracy and 

 working speed. 



One of the chief objections which is raised against wireless tele- 

 graphy is that it is possible to work only two or a very limited 

 number of stations in the immediate vicinity of each other without 

 causing mutual interference, or producing a jumble by the confusion 

 of the different messages. This objection appears to be much more 

 serious to that section of the public which knows little or nothing of 

 telegraphy in general than to telegraph engineers, who know that 

 without organisation and discipline the same interference would occur 

 in the great majority of ordinary land telegraphs. For example, 

 there is an " omnibus " line between Cork and Crookbaven. On this 



